JP5622225B2 - Beam control apparatus, particle beam irradiation apparatus, and control method thereof - Google Patents

Description

  The present invention relates to accelerator science, and more particularly to a beam control apparatus, a particle beam irradiation apparatus, and a control method thereof that can obtain a desired dose.

Conventionally, in particle beam cancer treatment, the intensity of an outgoing beam extracted from a synchrotron is controlled by adjusting an RF-KO voltage applied to an RF-KO electrode installed in the synchrotron ( Patent Document 1).
In an electromagnet in a synchrotron, a frequency due to a commercial frequency appears as a power supply ripple due to a process such as rectification. For example, in the beam spill due to slow beam extraction (Non-Patent Document 1), which is divided and extracted several times from the synchrotron, a frequency ripple of 50 Hz or 60 Hz equal to the commercial frequency and its multiple appears.

  The fluctuation of the magnetic field due to the power ripple of the electromagnet in the ring of the synchrotron causes a change in the separatrix area generated by the perturbation of the multipole magnetic field corresponding to the resonance order of the betatron oscillation. Therefore, particles existing in the vicinity of the separatrix are extracted to the resonance region by reducing the separatrix area.

FIG. 9 is a diagram illustrating a state in which the separatrix area S in the phase space varies greatly due to the conventional power supply ripple. Here, X ′ is dX / dY when the beam traveling direction is Y, and is the angle of the particle with respect to the beam traveling direction.
As shown in FIG. 9, since the area increase ΔS1 and the area decrease ΔS2 that are changes in the separatrix area S occur according to the power supply ripple frequency, a power supply ripple frequency component also appears in the output beam from the synchrotron as a result. is there. Particles existing in the shaded area near the separatrix s are taken out to the resonance region by the change of the separatrix area S (area increase ΔS1, area decrease ΔS2).

Japanese Patent Laid-Open No. 5-198397 JP-A-8-203700

E. Wilson, “Non-Linearities and Resonances”, CERN 94-01 v 1 (1994) pp. 239. Takuji Furukawa, et al., “Design study of a raster scanning system for moving target irradiation in heavy-ion radiotherapy”, Medical Physics 34 (2007) pp.1085-1097.

However, in the case of scanning irradiation for particle beam therapy (Non-Patent Document 2) and the like, a constant emission beam intensity (irradiation dose rate) is required.
For this reason, large beam spill ripple should be avoided as much as possible because it results in over-dosing of the treatment plan during spot movement outside of dose control.
Therefore, in Patent Document 2, in order to suppress the beam spill ripple caused by the power supply ripple of the electromagnet in the synchrotron, a high frequency component having an effect of canceling the influence of the power supply ripple is superimposed on the current pattern of the quadrupole electromagnet only in the extraction section. And how to perturb.

Specifically, Patent Document 2 adds a perturbation to the quadrupole electromagnet power supply so as to cancel the influence of the power supply ripple of the electromagnet in the ring of the synchrotron.
However, this method has a drawback that it is complicated as a system and is vulnerable to a slight ripple frequency and phase shift. There is also a problem that in order to put it into practical use, it is necessary to gain insight into these current patterns every day.
In view of the above circumstances, an object of the present invention is to provide a beam control apparatus, a particle beam irradiation apparatus, and a control method thereof that are low in cost and can prevent a dose fluctuation and obtain a set amount of dose.

In order to achieve the above object, a beam control apparatus according to the first aspect of the present invention is a beam control apparatus that includes a synchrotron and extracts a particle beam using resonance of betatron oscillation from the synchrotron. A multipole electromagnet corresponding to the order of resonance for generating a separatrix of a particle beam in the synchrotron , a converging quadrupole electromagnet for converging the particle beam in the synchrotron , and the particle beam. A divergence quadrupole electromagnet for divergence and beam control means, wherein the beam control means sets the magnetic field intensity of the multipole electromagnet so as to obtain a desired dose, and the fluctuation of the dose of the beam of the particle beam is If not within the fixed amount, increase the magnetic field strength of the multipole electromagnet and reduce the number of the converging quadrupole electromagnet or the diverging quadrupole electromagnet. Also, control is performed to change the excitation amount of any of the particle beam beams so that the separatrix area of the particle beam beam becomes a predetermined size, and fluctuation of the dose of the particle beam beam is within a predetermined amount, and the particle beam beam The beam spill ripple is kept below a predetermined amount .

  The particle beam irradiation apparatus according to the second aspect of the present invention includes the beam control apparatus according to the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a beam control apparatus control method comprising a synchrotron and beam control means for controlling a device for controlling a particle beam in the synchrotron, A control method of a beam control apparatus for extracting a particle beam using resonance, wherein the beam control unit sets a magnetic field strength of the multipole electromagnet so as to obtain a desired dose, and the particle beam If the fluctuation of the dose of the beam is not within a predetermined amount, the magnetic field strength of the multipole magnet corresponding to the order of resonance for generating the separatrix of the particle beam in the synchrotron is set as the focusing quadrupole magnet or the diverging quadrupole electromagnet. while maintaining the separatrix area of the particle beam by changing at least one of the amount of excitation of the desired size, to control high Thus, the dose fluctuations of the particle beam as a predetermined amount, thereby reducing the beam pill ripple of the particle beam in a predetermined amount or less.

  The particle beam irradiation apparatus control method according to the fourth aspect of the present invention is a particle beam irradiation apparatus control method for performing the beam control apparatus control method according to the third aspect of the present invention.

  According to the present invention, it is possible to realize a beam control apparatus, a particle beam irradiation apparatus, and a control method thereof that can prevent a dose fluctuation and obtain a set amount of dose at low cost.

It is a figure which shows the synchrotron and outgoing transport line of the beam control apparatus in the particle beam irradiation apparatus of embodiment concerning this invention. It is a block diagram in the case of implementing this embodiment. It is a figure which shows that a separatrix area reduces from S1 to S2. Changes in the hexapole magnetic field strength and separatrix area of the separatrix generating hexapole magnet when the absolute value of the difference between the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding a multiple of 3) is constant. It is a figure which shows a relationship. It is a figure which shows that a separatrix area expands from S2 to S3. Changes in the hexapole magnetic field strength and separatrix area of the separatrix generating hexapole magnet when the absolute value of the difference between the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding multiples of 3) is increased. It is a figure which shows a relationship. It is a flowchart which shows the procedure of the slow taking-out by the tertiary resonance of betatron vibration. It is a figure which shows the effect by having implemented slow extraction by the 3rd resonance of betatron vibration. It is a figure showing a mode that the separatrix area on phase space is fluctuate | varied largely by the conventional power supply ripple.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows the synchrotron 2 and the outgoing transport line 19 of the beam control apparatus 1 in the particle beam irradiation apparatus R of the embodiment. The actual particle beam irradiation apparatus R includes an incident line to the synchrotron 2 and an RF (Radio Frequancy) acceleration cavity in addition to the equipment shown in FIG. 1, but is omitted in FIG.

<Particle beam irradiation device R>
The particle beam irradiation apparatus R is an apparatus that irradiates a target affected area with a predetermined dose of a particle beam such as carbon ions by scanning irradiation or the like.
The particle beam irradiation apparatus R includes a beam control apparatus 1 that controls the beam of the particle beam in the synchrotron 2.

<Synchrotron 2 of beam control device 1 in particle beam irradiation device R>
The synchrotron 2 of the beam control device 1 is an annular device that accelerates charged particles such as carbon nuclei to high energy by synchronizing the acceleration high-frequency period with the particle rotation period. The synchrotron 2 corresponds to an “accelerator”.

  The synchrotron 2 includes, as main components, a deflection electromagnet 3 for keeping the beam of the particle beam traveling in the synchrotron 2 in a circular orbit, and a converging quadrupole electromagnet 4 for converging the spread of the beam of the particle beam on the circular orbit. A divergence quadrupole electromagnet 5 that diverges the spread of the beam, a hexapole electromagnet 6 for separatrix generation that excites the third-order resonance of betatron oscillation and divides and forms a stable circulation region and a resonance region in phase space, A beam profile monitor 7 in the ring of the synchrotron 2 for monitoring the irradiation amount, a beam profile monitor 8 of the outgoing transport line 19, and a deflector electrode 9 for emitting the particle beam toward the outgoing transport line 19. Yes. Separatrix means between the stable circulation region and the resonance region.

Control of the particle beam irradiation apparatus R is performed by a control means (not shown). The control means of the particle beam irradiation apparatus R includes beam control means that controls the equipment that controls the beam of the particle beam of the beam control apparatus 1.
The control means and beam control means are configured by a computer, a circuit, and the like.

<Removal of particle beam from synchrotron 2>
A large number of particles orbiting the orbit in the synchrotron 2 shown in FIG. 1 are horizontal (parallel to the paper surface of FIG. 1: X-axis direction) or vertical direction (perpendicular to the paper surface of FIG. 1: Z-axis). Around the direction of vibration. This vibration is called betatron vibration, which can be controlled by the converging quadrupole electromagnet 4, the diverging quadrupole electromagnet 5, and the like. The Y-axis direction is the direction in which the particle beam travels in the synchrotron 2 (circumferential tangential direction in the synchrotron 2), and the X-axis direction is the direction perpendicular to the Y-axis direction in the horizontal plane.

After these particles are accelerated by an RF acceleration cavity (not shown) and reach a maximum energy, a part of a large number of particles orbiting in the synchrotron 2 is transferred to a particle beam as an RF-KO electrode (not shown). 2), by applying an electric field by an RF-KO voltage in the treatment room (irradiation room) using the deflector electrode 9, the outgoing transport following the irradiation apparatus (not shown) that irradiates the particle beam taken out to the irradiation object in the treatment room (irradiation room) The light is emitted toward the line 19.
Specifically, in order to extract the beam of particle beam in the synchrotron 2 toward the outgoing transport line 19 following the irradiation device outside the synchrotron 2, the beam of particle beam distributed near the center in the synchrotron 2 is An electric field based on an RF-KO voltage is applied between the RF-KO electrodes in a vertical and horizontal direction with respect to the orbit, and the beam size of the particle beam is expanded in the horizontal direction. The emission of the particles is performed by utilizing the resonance of the betatron vibration of the particles traveling on the orbit in the synchrotron 2.

Specifically, the RF-KO electrode is perpendicular to the circular orbit and in the horizontal direction (parallel to the paper surface of FIG. 1) with respect to the beam traveling on the circular orbit of the synchrotron 2 before being extracted to the outgoing transport line 19. ) Is applied with an electric field generated by a frequency-modulated and amplitude-modulated RF-KO voltage that resonates with the betatron oscillation, and the width of the beam of the particle beam traveling on the circular orbit is widened, whereby a part of the particle beam is deflected. The electrode 9 is put into two electrodes. When the beam enters the two electrodes of the deflector electrode 9, the particle beam is kicked outward by the electric field in the deflector electrode 9 and extracted toward the outgoing transport line 19.
When the RF-KO voltage is off, the increase in the particle beam size stops, so that the particle beam is not taken out from the deflector electrode 9, so that the irradiation can be stopped.

  Here, the change of the separatrix area S which is the area of the separatrix s shown in FIG. 9 is suppressed. Therefore, while maintaining the separatrix area S, the separatrix generation six of the multipolar magnet corresponding to the order of resonance used for the generation of the separatrix in the slow extraction of the particle beam by the third order resonance of the betatron vibration that is a vibration that circulates around the synchrotron 2. The beam control means controls the magnetic field intensity of the polar electromagnet 6 to be high.

As a result, the change in the separatrix area S (area increase ΔS1 and area decrease ΔS2 in FIG. 9) is reduced as compared with the same amount of power supply ripple as in the past. However, when the magnetic field strength of the separatrix generating hexapole electromagnet 6 is increased, the separatrix area S is reduced.
Therefore, in order to keep the separatrix area S at a predetermined size, the beam control means, among the converging quadrupole electromagnets 4 and the diverging quadrupole electromagnets 5, adjusts with the increase in the magnetic field strength of the separatrix generating hexapole electromagnet 6. Resonance condition n / m (where n is a multiple of m) of the m-th order (where m is the number of the separatrix s (see FIG. 3)) the betatron frequency in the linear component by changing at least one of the excitation amounts The separatrix area S of the stable region is made larger from the natural number except for.

For example, the beam control means increases the excitation amount of the converging quadrupole electromagnet 4 so that the betatron frequency in the linear component is separated from the m-th order resonance condition n / m, and the separatrix area S of the stable region is increased.
In this way, by suppressing changes in the separatrix area S of the beam of particle beams (area increase ΔS1 and area decrease ΔS2 in FIG. 9), the number of particles that have been extracted into the resonance region by reducing the separatrix area S (FIG. 9). 9) (the number of particles in the area increase ΔS1 and area decrease ΔS2) can be reduced, and as a result, beam spill ripple due to power supply ripple can be reduced.

<Operation (phenomenon) of slow extraction of particle beam from synchrotron 2 of beam controller 1>
FIG. 2 shows a block diagram in the case of carrying out the present embodiment, taking as an example the slow extraction of the particle beam due to the third-order resonance of betatron oscillation.
FIG. 3 is a diagram illustrating that the separatrix area S of the separatrix s is reduced from S1 to S2. Here, X ′ is dX / dY when the beam traveling direction is Y, and is the angle of the particle with respect to the beam traveling direction. The same applies to FIGS. 5 and 8 described later.
In FIG. 2 (1), when only the magnetic field strength of the separatrix generating hexapole electromagnet 6 (see FIG. 1) in the synchrotron 2 is increased by the beam control means, the separatrix area S of the separatrix s is obtained as shown in FIG. Is reduced from S1 (indicated by a broken line in FIG. 3) to S2 (indicated by a solid line in FIG. 3).

FIG. 4 is a diagram showing the relationship between the hexapole magnetic field strength of the separatrix generating hexapole electromagnet 6 and the change in the separatrix area S when the linear betatron frequency is constant. In FIG. 4, the horizontal axis represents the hexapole magnetic field strength of the separatrix generating hexapole electromagnet 6, and the vertical axis represents the separatrix area S, the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding a multiple of 3). The absolute value of the difference is taken.
As shown in FIG. 4, when the linear betatron frequency is kept constant and the hexapole magnetic field intensity of the separatrix generating hexapole electromagnet 6 is increased by the beam control means, it can be seen that the separatrix area S decreases.

Therefore, in (2) of FIG. 2, the dose is measured using either or both of the beam profile monitor 7 in the ring of the synchrotron 2 and the beam profile monitor 8 in the outgoing transport line 19.
Then, in (3) of FIG. 2, at least one of the amount of excitation of the converging quadrupole electromagnet 4 and the diverging quadrupole electromagnet 5 is beam-controlled so as to maintain a separatrix area S where the dose to be measured is a predetermined amount. By changing the means and separating the linear betatron frequency from the resonance condition n / 3 (n is a natural number excluding a multiple of 3), the separatrix area S2 is expanded to the separatrix area S3 as shown in FIG. FIG. 5 is a diagram illustrating that the separatrix area S of the separatrix s increases from S2 to S3.

Thereafter, in (4) of FIG. 2, the fluctuation of the dose is measured, and when the fluctuation of the dose exceeds a predetermined amount, the process proceeds to (1) of FIG.
The control shown in FIG. 2 is performed by the beam control means until the fluctuation of the beam dose of the particle beam in the synchrotron 2 is within a predetermined amount and the separatrix area S becomes a desired size.
FIG. 6 shows the hexapole magnetic field strength of the separatrix generating hexapole electromagnet 6 when the absolute value of the difference between the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding a multiple of 3) is increased. It is a figure which shows the relationship of the change of the separatrix area. In FIG. 6, the horizontal axis represents the hexapole magnetic field strength of the separatrix generating hexapole electromagnet 6, the vertical axis represents the separatrix area S, and the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding a multiple of 3). ) Is the absolute value of the difference.

As shown in FIG. 6, when the absolute value of the difference between the linear betatron frequency and the resonance condition n / 3 (n is a natural number excluding multiples of 3) is increased, the hexapole of the separatrix generating hexapole electromagnet 6 It can be seen that the size of the separation area S is maintained even if the magnetic field intensity is increased by the beam control means.
The above phenomenon will be described qualitatively.
The separatrix s of the particle beam is greater as the absolute value of the difference between the linear betatron frequency when the particle beam orbits the synchrotron 2 and the resonance condition n / m is larger. ) Becomes larger. Further, the larger the multipolar magnetic field strength of the separatrix generating hexapole electromagnet 6 used as the perturbation, the smaller the separatrix area S (see FIG. 8). The power supply ripple at the commercial frequency (50 Hz or 60 Hz) changes the linear betatron frequency and the multipolar magnetic field strength of the separatrix generating hexapole electromagnet 6, and therefore the separatrix area S also changes.

  Therefore, both the absolute value (A) of the difference between the linear betatron frequency and the resonance condition n / m and the multipolar magnetic field strength (B) of the separatrix generating hexapole electromagnet 6 are maintained while maintaining the separatrix area S. In the larger state, the absolute value (A) of the difference between the linear betatron frequency and the resonance condition n / m and the multipolar magnetic field strength (B ) Changes (changes ΔA and ΔB), ΔA / A and ΔB / B become smaller, so that the influence of the power supply ripple can be reduced.

<Slow extraction procedure by third-order resonance of betatron oscillation>
Next, a procedure for slow extraction by the third-order resonance of betatron vibration will be described with reference to FIG. FIG. 7 is a flowchart showing a procedure of slow extraction by the third-order resonance of betatron vibration.
The following control of the beam control apparatus 1 is performed by the beam control means described above. Further, in the following flow, a description will be given of the control for setting the fluctuation of the particle beam to be within a predetermined amount and setting the separatrix area S of the particle beam to a predetermined size.

  First, in S101 of FIG. 7, the magnetic field intensity of the separatrix generating hexapole electromagnet 6 is set so as to obtain a desired dose. Subsequently, the dose is measured using either or both of the beam profile monitor 7 in the ring of the synchrotron 2 shown in FIG. 1 and the beam profile monitor 8 in the outgoing transport line 19 (S102). Then, based on the measured dose, a separatrix area S is calculated (S103).

Subsequently, it is determined whether or not the fluctuation due to the power source ripple frequency component of the measured beam dose of the particle beam is within a predetermined amount and the separatrix area S is a predetermined size (S104).
If the fluctuation of the measured dose of the particle beam is within a predetermined amount and the separatrix area S is a predetermined size (Yes in S104), the process ends.
When the measured particle beam beam fluctuation is within a predetermined amount and the separatrix area S is not a predetermined size (No in S104), the measured particle beam beam fluctuation in S105 (FIG. 9). It is determined whether or not the area increase ΔS1 and area decrease ΔS2) of the separatrix s are within a predetermined amount (S105).

  If the measured fluctuation of the beam dose of the particle beam is not within the predetermined amount (No in S105), the magnetic field strength of the separatrix generating hexapole electromagnet 6 is increased. Thereby, as shown in FIG. 3, the separatrix area S of the separatrix s is reduced from S1 to S2 (S106). Thereafter, the process proceeds to S102.

On the other hand, if it is determined in S105 that the fluctuation of the measured dose of the particle beam is within a predetermined amount (Yes in S105), the separation quadrupole electromagnet 4 or the divergence is not obtained because the separatrix area S is not a predetermined size. The amount of excitation of at least one of the quadrupole electromagnets 5 is changed and adjusted so that the separation area S becomes a predetermined size. For example, when the separatrix area S is smaller than the desired size, the separation of the linear betatron frequency from the resonance condition n / 3 (where n is a natural number excluding multiples of 3), the separatrix area S2 is reduced as shown in FIG. It expands to the separatrix area S3. Thereafter, the process proceeds to S102.
The above is the slow extraction procedure by the third-order resonance of the betatron oscillation shown in FIG.

FIG. 8 shows the effect obtained by performing the slow extraction by the third resonance of the betatron vibration described above.
As shown in FIG. 8, the amount of fluctuation of the separatrix area S is smaller than the same amount of power supply ripple shown in FIG. 9 (corresponding to the area increase ΔS1 and area decrease ΔS2 of the separatrix area S in FIG. 9). Therefore, it is possible to reduce the area where the particles extracted to the resonance area exist due to the change in the separatrix area S (areas ΔS1 and ΔS2 surrounded by the broken line in FIG. 9). As a result, the power supply ripple frequency component that appears in the emitted beam spill ripple can be suppressed.

According to the above configuration, the influence itself on the beam due to the power supply ripple of the electromagnet in the ring can be suppressed without adding perturbation or the like to the power supply, and the cost is low.
In addition, it is possible to supply a constant output beam intensity (irradiation dose rate) with a low ripple as required by scanning irradiation for particle beam therapy. Furthermore, daily current pattern adjustment is not required, and reproducibility is high and practically excellent.

  In the above embodiment, the third-order resonance of the betatron vibration and the slow extraction of the particle beam using the hexapole magnet are exemplified, but the secondary resonance of the betatron vibration and the octupole electromagnet, or the fourth resonance and the octupole As long as it corresponds to the order of resonance, such as an electromagnet, it may be combined with another multipolar electromagnet.

  Further, the present invention is not limited to the slow extraction using the RF-KO electrode. For example, a beam intensity control device (beam control device) using betatron frequency control by changing a quadrupole electromagnet excitation current, and a beam intensity control device (beam control device using a betatron frequency control method by changing beam energy) ). Alternatively, it may be a beam accelerator (beam controller) such as an induction accelerator or a high-frequency accelerator capable of changing beam energy.

  Further, in the beam intensity control device (beam control device) using the betatron frequency control method by changing the quadrupole electromagnet excitation current, the excitation current may be changed by controlling the power supply of the quadrupole electromagnet. . A plurality of quadrupole electromagnets are generally provided in the synchrotron, but the effect can also be obtained by controlling at least one of them.

1 Beam control device 2 Synchrotron 4 Convergence quadrupole electromagnet (convergence electromagnet, equipment)
5 Divergent quadrupole magnets (divergent electromagnets, equipment)
6 Hexapolar electromagnets for generating separatrix (multipolar electromagnets, equipment)
R Particle beam irradiation equipment s Separatrix S Separatrix area

Claims (6)

A beam control apparatus comprising a synchrotron and for extracting a particle beam using resonance of betatron oscillation from the synchrotron,
A multipole electromagnet corresponding to the order of resonance for generating a separatrix of a particle beam in the synchrotron;
A converging quadrupole magnet for converging the particle beam in the synchrotron, and a diverging quadrupole magnet for diverging the particle beam;
Beam control means,
The beam control means includes
Set the magnetic field strength of the multipole electromagnet to achieve a desired dose,
If the fluctuation of the beam dose of the particle beam is not within a predetermined amount,
While increasing the magnetic field strength of the multipolar electromagnet, the amount of excitation of at least one of the converging quadrupole electromagnet or the diverging quadrupole electromagnet is changed so that the separatrix area of the particle beam becomes a predetermined size. The beam control apparatus according to claim 1, wherein the control is performed so that the fluctuation of the dose of the particle beam is within a predetermined amount, and the beam spill ripple of the particle beam is suppressed to a predetermined amount or less . The beam control means changes the separatrix area by changing the excitation amount of at least one of the converging quadrupole electromagnet and the diverging quadrupole electromagnet to separate the linear betatron frequency from the resonance condition. The beam control device according to claim 1, wherein the beam control device is maintained in a desired size.   A particle beam irradiation apparatus comprising the beam control apparatus according to claim 1. Beam control for taking out a particle beam using resonance of betatron oscillation from the synchrotron, comprising a synchrotron and beam control means for controlling a device for controlling the particle beam in the synchrotron An apparatus control method comprising:
The beam control means includes
Set the magnetic field strength of the multipole electromagnet to achieve a desired dose,
If the fluctuation of the beam dose of the particle beam is not within a predetermined amount,
The magnetic field strength of the multipole magnet corresponding to the order of resonance for generating the separation beam of the particle beam in the synchrotron is changed by changing the excitation amount of at least one of the focusing quadrupole magnet or the diverging quadrupole magnet. The particle beam beam spill ripple is reduced to a predetermined amount or less by keeping the particle beam beam separatrix area at a desired size and controlling it to a high level so that the dose fluctuation of the particle beam is within a predetermined amount. A control method for a beam control device. The beam control means changes the separatrix area by changing the excitation amount of at least one of the converging quadrupole electromagnet and the diverging quadrupole electromagnet to separate the linear betatron frequency from the resonance condition. The beam control apparatus control method according to claim 4, wherein the beam control apparatus maintains a desired size.   A method for controlling a particle beam irradiation apparatus, wherein the method for controlling a beam control apparatus according to claim 4 or 5 is performed.

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